[FFmpeg-devel] [PATCH 3/8] lavd/avdevice: add device iterators

[Nicolas George]

Le primidi 11 ventôse, an CCXXII, Lukasz Marek a écrit :
> Just noticed bug in it - there was AV_CLASS_CATEGORY_DEVICE_INPUT as
> second category in output iterators
> Updated patch attached.

I like that version. Just a few remarks.

> >From 3f22a48b1a95856fca48306ffab9333721bde156 Mon Sep 17 00:00:00 2001
> From: Lukasz Marek <lukasz.m.luki at gmail.com>
> Date: Sat, 22 Feb 2014 23:32:55 +0100
> Subject: [PATCH 3/8] lavd/avdevice: add device iterators
> 
> TODO: minor bump, update doc/APIChanges
> 
> Signed-off-by: Lukasz Marek <lukasz.m.luki at gmail.com>
> ---
>  libavdevice/avdevice.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
>  libavdevice/avdevice.h | 16 ++++++++++++++++
>  2 files changed, 62 insertions(+)
> 
> diff --git a/libavdevice/avdevice.c b/libavdevice/avdevice.c
> index 9e2b7d5..e59942f 100644
> --- a/libavdevice/avdevice.c
> +++ b/libavdevice/avdevice.c
> @@ -37,6 +37,52 @@ const char * avdevice_license(void)
>      return LICENSE_PREFIX FFMPEG_LICENSE + sizeof(LICENSE_PREFIX) - 1;
>  }
>  
> +static void *av_device_next(void *prev, int output,
> +                            AVClassCategory c1, AVClassCategory c2)
> +{
> +    const AVClass *pc;

> +    AVClassCategory category = AV_CLASS_CATEGORY_NA;
> +    while (category != c1 && category != c2) {

I suspect this is a case where a do...while loop would make things more
readable:

	do {
	} while (pc->category != c1 && pc->category != c2);

By testing the condition after pc is updated, you avoid the need for a dummy
category at the beginning.

> +        if (output) {
> +            if (!(prev = av_oformat_next(prev)))
> +                break;
> +            pc = ((AVOutputFormat *)prev)->priv_class;
> +        } else {
> +            if (!(prev = av_iformat_next(prev)))
> +                break;
> +            pc = ((AVInputFormat *)prev)->priv_class;
> +        }
> +        if (!pc)
> +            continue;
> +        category = pc->category;
> +    }
> +    return prev;
> +}
> +
> +AVInputFormat *av_input_audio_device_next(AVInputFormat  *d)
> +{
> +    return av_device_next(d, 0, AV_CLASS_CATEGORY_DEVICE_AUDIO_INPUT,
> +                          AV_CLASS_CATEGORY_DEVICE_INPUT);
> +}
> +
> +AVInputFormat *av_input_video_device_next(AVInputFormat  *d)
> +{
> +    return av_device_next(d, 0, AV_CLASS_CATEGORY_DEVICE_VIDEO_INPUT,
> +                          AV_CLASS_CATEGORY_DEVICE_INPUT);
> +}
> +
> +AVOutputFormat *av_output_audio_device_next(AVOutputFormat *d)
> +{
> +    return av_device_next(d, 1, AV_CLASS_CATEGORY_DEVICE_AUDIO_OUTPUT,
> +                          AV_CLASS_CATEGORY_DEVICE_OUTPUT);
> +}
> +
> +AVOutputFormat *av_output_video_device_next(AVOutputFormat *d)
> +{
> +    return av_device_next(d, 1, AV_CLASS_CATEGORY_DEVICE_VIDEO_OUTPUT,
> +                          AV_CLASS_CATEGORY_DEVICE_OUTPUT);
> +}
> +
>  int avdevice_app_to_dev_control_message(struct AVFormatContext *s, enum AVAppToDevMessageType type,
>                                          void *data, size_t data_size)
>  {
> diff --git a/libavdevice/avdevice.h b/libavdevice/avdevice.h
> index 28344ca..47bf8f4 100644
> --- a/libavdevice/avdevice.h
> +++ b/libavdevice/avdevice.h
> @@ -66,6 +66,22 @@ const char *avdevice_license(void);
>   */
>  void avdevice_register_all(void);
>  
> +/**
> + * If d is NULL, returns the first registered input audio/video device,
> + * if d is non-NULL, returns the next registered input audio/video device after d
> + * or NULL if d is the last one.
> + */
> +AVInputFormat *av_input_audio_device_next(AVInputFormat  *d);
> +AVInputFormat *av_input_video_device_next(AVInputFormat  *d);
> +
> +/**
> + * If d is NULL, returns the first registered output audio/video device,
> + * if d is non-NULL, returns the next registered output audio/video device after d
> + * or NULL if d is the last one.
> + */
> +AVOutputFormat *av_output_audio_device_next(AVOutputFormat *d);
> +AVOutputFormat *av_output_video_device_next(AVOutputFormat *d);
> +
>  typedef struct AVDeviceRect {
>      int x;      /**< x coordinate of top left corner */
>      int y;      /**< y coordinate of top left corner */

Regards,

-- 
  Nicolas George
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